Waiting on the parts I ordered I thought about what to do next. For the next week I see two major topics:

• Research

• the next level of Prototype

For research I'm in the moment most interested in how the tree moves and how much energy is in the movement. So, besides some literature research, I want to build a arduinobased linear movement logger, which is basically two pipes which snuggly fit into each other, inside there will be ultrasonic or IR distance sensor and hooked to that is an Arduino which logs the data. I plan to build several of these to test different trees and different mountings.

A second version will have a strong spring in it, so together with the position data I can calculate the force for every point in time, with that also the work done and therefore the minimal energy which the tree can give away.

The endgoal for the working prototypes is to build something which fullfils this requirements:

• easy to build (good documentation, no use of expensive tools)
• versatile (so you can use it also for your wave energy power plant)
• able to harvest power over a big range of wind velocities
• as cheap as possible

For the next working prototype I want to build a Harvester which can deliver >2W of peak power. I'm not sure yet what I will use as a generator and if I go the route with strings and a winch or rack and piston (see my brainstorming post), but I know that it will build in some sort of power/energymeter+logging and I want to integrate a battery so I can really use the power (e.g. for charging my phone). As a generator I look currently in bigger stepper motors, hover board or electrical bike motors, bycycle generators and DIY generators for wind turbines. But I think at least for the next prototype I will go the easy road and not build the generator myself.

Also the concept with collecting the power with pressure in liquids and using a central turbine to generate the power has to be tested, but this is something which has a lower priority and I will probably only look into if I manage to get into the final round of the Hackaday Prize.

Stay tuned for the next update!